To Örebro University

The incidence of oral squamous cell carcinoma (OSCC) in Sweden increased by 30 % between 2008 and 2021. Surgical resection with clear margins is the first line of treatment. The aim of the present thesis was to evaluate preoperative assessments and intraoperative techniques to improve the surgical margins, while preserving healthy tissue to optimise the functional outcome.

Study I prospectively included 40 patients with oral tongue cancer (SCCOT). Depth of invasion (DOI) measured with ultrasound (US) was compared to magnetic resonance imaging (MRI). Histopathological DOI was the gold standard. DOI by US was the most accurate method. MRI overestimated DOI and could not assess a substantial proportion of the tumours. Study II compared US-assisted resection in 34 patients with SCCOT, to resections performed without US in 76 historical controls. Insufficient deep resection margins (<5.0mm) were seen in 8 of 34 patients (23.5%) in the study group, compared to 31 of 76 (40.8%) in the conventional group (unadjusted RR 0.58, 95% CI 0.30-1.12, unadjusted mean difference 1.4mm, 95% CI 0.1-2.7, adjusted mean difference not significant). US-assisted resection has the potential to improve the deep resection margins, though larger studies with more robust data are needed. Study III examined visualisation of mucosal tumour borders with narrow band imaging (NBI) compared to white light (WL) in 34 patients with OSCC. NBI was not found to better delineate the true tumour borders compared to WL. Study IV retrospectively investigated preoperative predictors for local recurrence (LR) in gingival cancers of the mandible; treated with marginal mandibulectomy in 67 patients. Cox regression analyses found edentulous patients, more advanced pT-stage and positive soft tissue margins to increase the risk for LR.